Urmia Lake, the largest hypersaline lake in the Middle East, has seen a 90% reduction in its surface area during the last 30 years due to decreased water supply to the lake. The drastic environmental degradation of the lake is a national concern but there are contrasting views on how to proceed. While one group blames the natural climate cycles, the other seeks experts to investigate the reasons for the lake's desiccation. However, there is a paucity of robust decadal to millennial scale data of climate variability and thus the main causes behind the reduction of the lake are the subject of huge debates. Difficulties in establishing a robust chronology made it challenging to decipher the existing paleoclimate records from Urmia Lake. This study, for the first time, has provided a well-calibrated chronology and investigated climate variability and hydrology of the region since 11,600 BP. Comparative calibrated radiocarbon ages from different sediment constituents extracted from 0.65- and 5.4-meter intervals in the sediment core suggest a 560- and 719-year correction for reservoir effect on bulk sediment and fecal pellets radiocarbon dates, respectively. Down-core variations in paleo-dust, paleo-hydrology and paleo-redox proxies at an average resolution of 2.5 yr suggest several episodes of wet and dry conditions associated with high and low lake levels. Variation in XRF profiles of Al and Si covary closely with the record of North Atlantic ice rafted debris events and Holocene reconstruction of sunspots, indicating the influence of climate forcing on the hydrological condition of the Urmia Lake. Paleo-rainfall reconstruction reveals that the mean annual precipitation (MAP) over the Urmia Lake region has varied from 183 to 372 mm y (super -1) and suggests wet conditions were dominant during the early Holocene and dry conditions became more frequent toward the late Holocene. Considering the facts that the drastic reduction in the Urmia Lake surface area appeared during the last 30 years and the 55-year mean annual precipitation over the lake returned an average of 340 mm- very close to maximum Holocene paleo-rainfall reconstruction - it can be concluded that the extensive anthropogenic activities and poor water management over the last few decades had more impact on water availability to the lake compare to natural climate cycles
